Small industrial locomotives are typically used to move one to several rail cars in and around a factory, a mine, a small rail yard, a shipping hub and the like. These are typically small locomotives with two or more axles attached directly to the locomotive frame or by means of swiveling truck assemblies that are attached to the locomotive car body. An example of a small industrial locomotive is shown in FIG. 1.
For larger industrial applications, used or new switcher locomotives or used line-haul locomotives are often employed. An example of a switcher locomotive is shown in FIG. 2. An example of a line-haul locomotive is shown in FIG. 3.
Railcar movers are another alternative for moving rail cars about a rail yard. These are road-rail vehicles capable of traveling on both roads and rail tracks. They are fitted with couplers for moving small numbers of railroad cars around in a rail siding or small yard. Railcar movers are typically less expensive than switcher locomotives and more productive than manual moving of cars. They are more versatile since they can travel on road wheels to the cars they need to move, instead of requiring clear track.
There are basically two types of mobile railcar movers available. The first type developed in the late forties utilizes steel driven rail wheels for motive effort on rail track. Off road movement is developed by engaging rubber tires with drive sprocket extensions on the rail wheels. The second type developed in the early seventies generates its motive effort on the rail through rubber tires. Off road movement uses the same drive system and rubber tires.
The tasks of marshaling of railcars in a rail yard or spotting railcars in an industrial facility are usually done by switcher locomotives, industrial locomotives or railcar movers. The problem that has developed in relatively recent times is the shortage of suitable equipment to do switching and spotting functions. In the past, larger locomotives that became obsolete and surplus to the railroads for line-haul service could be reused in lighter duty industrial and switcher service. Nowadays, more often than not, this is no longer possible. Today because of their sheer size and power, currently available surplus line-haul locomotives are unsuitable for any service other than that for which they were originally designed.
Surplus four-axle locomotives with two-axle trucks from line haul service are the type of locomotive that are sought after for switching and industrial applications and therefore have an intrinsic value greater than the larger six-axle locomotives with their pair of three-axle trucks. The present situation is that the majority of available surplus line-haul locomotives have been replaced by newer locomotives and are the six-axle type which cannot be economically converted for the switching and industrial service and are often discarded as scrap.
There is an on-going demand for new and replacement switcher and industrial locomotives that is now being mostly met by the reworking of older locomotives from limited sources, by the manufacturing of new industrial locomotives that incorporate reclaimed parts from limited sources, and by railcar movers.